摘要
研究了Ti_3Al-Nb(Ti-24Al-14Nb-3V-0.5Mo)(at％)合金时效过程中组织与性能的变化。结果表明,合金经α_2+β两相区1000℃lh/WQ固溶处理后,分别在650、750和850℃时效24h空冷,会使其析出二次针状α_2相和大量“O”相。随着时效温度的升高,初生α_2相长大,二次针状α_2相和“O”相球化。“O”相除以块状形式存在于初生α_2相周围外,还成片分布于初生α_2相内部。时效温度降低,室温,高温拉伸强度减小,而延伸率逐渐升高。时效态室温拉伸断口形貌为混合型断口。
The effect of aging treatment on the microstructure and tensile properties of Ti- 24A1-14Nb-3V-0.5Mo (at%) alloy has been studied. The results show that the acicular secondary α2-phase and 'O' phase are precipitated when the alloy is aged at 650 ℃ , 750 ℃ , and 850 ℃ respectively for 24 hours and coaled in air after solution-heated at 1000 ℃ for 1 hour and quenched in water. As the aging temperature increased, the primary α2 -phase coarsened, secondary α2-phase and 'O' -phase concentrated. The massive 'O'-phase is existed in the periphery of the primary α2, and the fine 'O' -phase is distributed all over the primary α2-phase. As the aging temperature decreases, the yield strength (σα2) and tensile strength (σb) decrease, but elongation (δ) increases at room and high temperature. The fracture of room temperature tensile sample aged at 850 ℃ is mixed cleavage dimples fractures.
